Link to the SI via primary direct methods

Máriássy, Michal; Vyskočil, L.; Mathiasová, A.

doi:10.1007/s007690000222

Cited by 19 publications

(21 citation statements)

References 2 publications

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“…Once the EP times were estimated using either eWf or TC, the amount of substance of KHP in mol kg −1 was calculated using eq 11. 7,11,27 i t t t i t i t nFmh…”

Section: Coulometric Titrationmentioning

confidence: 99%

Implementation of the Theoretical Coulometric Titration Curve in the Determination of the Amount of Substance of Potassium Hydrogen Phthalate: the Search for a Better Metrological Approach

Smith-Osorio

Torres-Quezada²,

Sandoval-Rojas

et al. 2022

ACS Omega

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In metrology, the certification of potassium hydrogen phthalate (KHP) as a reference material is made using the potential primary method of coulometric titration. Usually, this titration is performed in three steps at constant current, where two endpoint (EP) times are determined from the nonlinear regression that fits the empirical W-function (eWf) to the experimental data. As an alternative, we propose the implementation of the theoretical coulometric titration curve (TC). The TC allowed us to compute the KHP amount of substance, the influence of CO 2 in the system, the acid dissociation constants for carbonic and phthalic acids, assuming that those species are the only acids present during titration, and the EP times. The amount of substance of KHP estimated with the EP time and obtained from the TC was compared with the results of the eWf, and no statistical difference was found, while the amount of substance, when estimated directly as a parameter of the nonlinear regression of the TC, was lower. Therefore, the traditional method finds the total acidity of the dissolution, and our method finds the KHP purity. In addition, the acid dissociation constants for H 2 CO 3 and phthalic acid estimated in this work agreed with the data reported in the literature. Finally, the description of the coulometric system using the theoretical TC has a solid and well-known chemical support that is not present in the eWf; this fact is essential for the uncertainty budget and the scientific support for coulometry as a potential primary method.

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“…Once the EP times were estimated using either eWf or TC, the amount of substance of KHP in mol kg −1 was calculated using eq 11. 7,11,27 i t t t i t i t nFmh…”

Section: Coulometric Titrationmentioning

confidence: 99%

Implementation of the Theoretical Coulometric Titration Curve in the Determination of the Amount of Substance of Potassium Hydrogen Phthalate: the Search for a Better Metrological Approach

Smith-Osorio

Torres-Quezada²,

Sandoval-Rojas

et al. 2022

ACS Omega

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“…In this case, the coulometric titration has shown its considerable importance on the HCl concentration determination (Borges et al, 2004). It is worthwhile to point out that the concentration of NaCl was obtained by the gravimetric addition of the salt to the buffer solution (Máriássy et al, 2000), taking into account the purity of the salt, its molecular mass (Lide, 2000) and the water mass fraction of the buffer. The latter is important for the correct calculation of the electrolyte concentration, in mol⋅kg −1…”

Section: Discussionmentioning

confidence: 99%

Effect of NaCl and HCl concentrations on primary pH measurement for the certification of standard materials

Souza

Ordine

Fraga

et al. 2006

Braz. arch. biol. technol.

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“…There are some reports regarding a coulometric study for acidimetric standards, [3][4][5][6][7][8] oxidimetric-reductometric standards, [9][10][11][12][13][14] and precipitation standards. [15][16][17][18][19][20][21] Hioki et al reported on the dependence of the coulometric titration results on the amount of sample mass due to the influence by carbon dioxide for acidimetry. 4 Marinenko et al employed constant-current coulometry to determine the amount of chloride ion of NaCl, 15 and to evaluate the stability of NaCl solutions and the influence of the sample forms, solution and solid.…”

Section: 2mentioning

confidence: 99%

Influence of AgCl Precipitates on the Precipitation Titration of Sodium Chloride by Constant-Current Coulometry

et al. 2006

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The precipitation titration of sodium chloride with electrogenerated silver ion was studied. The production of a precipitate of silver chloride had a significant effect on the titration results because the precipitate involved unreacted chloride or unreacted silver ion. The accuracy of the method was investigated by changing the introduction time of a sodium chloride solution to the coulometric cell during the process of electrolysis, and examining the dependency on the sample size. The accuracy of the measurement of the precipitation titration is discussed.

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Link to the SI via primary direct methods

Abstract: The possible approaches to realising a link to the SI system and the status of primary direct methods in the traceability chain of chemical measurements are discussed. Some results obtained with the new coulometric standard system are presented.

Cited by 19 publications

References 2 publications

Implementation of the Theoretical Coulometric Titration Curve in the Determination of the Amount of Substance of Potassium Hydrogen Phthalate: the Search for a Better Metrological Approach

Implementation of the Theoretical Coulometric Titration Curve in the Determination of the Amount of Substance of Potassium Hydrogen Phthalate: the Search for a Better Metrological Approach

Effect of NaCl and HCl concentrations on primary pH measurement for the certification of standard materials

Influence of AgCl Precipitates on the Precipitation Titration of Sodium Chloride by Constant-Current Coulometry

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